Introduction: Patients with chronic obstructive pulmonary disease (COPD) dwellers of Mexico City may present a significant hypoxemia as a consequence of the lung disease and the altitude (2,240 m). These patients usually show a poorer hypoxemia during sleep.
Objective: To describe breathing during sleep in COPD patients residing at the altitude of Mexico City and the effect of supplementary oxygen.
Methods: A total of thirteen patients with COPD underwent standard polysomnography during two consecutive nights breathing room air or oxygen. Nine normal non-obese subjects matched by age and gender were also studied during one night breathing room air.
Results: Mean SaO2 during sleep was significantly lower in patients than in controls (85 +/- 5 vs. 93 +/- 2, p < 0.001). Oxygen desaturation was reversed with supplementary oxygen in all patients. However, sleep parameters were not different in patients and controls and did not change with oxygen. COPD patients were thachypneic in all sleep stages (18-20 vs. 13-14; p < 0.001) and this tachypnea persisted with oxygen.
Conclusion: A substantial nighttime desaturation was corrected with oxygen in all COPD patients studied at this altitude. Nonetheless, sleep quality was similar in patients and controls and did not change when patients breathed oxygen.